U.S. Pat. No. 4,148,866 discloses an improved synthesis loop for the production of ammonia which has a synthesis pressure of less than 100 atmospheres, a water absorption recovery system which utilizes low level heat recovered from the process for producing the synthesis gas to distill the ammonia-water mixture and an ammonia absorption refrigeration system.
U.S. Pat. No. 3,694,169 discloses a reactor for synthesising ammonia which comprises a pressure-resisting shell, a catalyst bed of annular section and a short axial heat exchanger. The reactant gas flows through the catalyst bed convergently towards an outlet near one end of the heat exchanger.